Nothing in the monster write-up suggests this. Is it a perpetual-motion machine after the final, successful craft check?

Can one stick a crowbar in there to gum up the gears and cause havoc?

They are immune to all magic, but I need one the PC's are going to discover to already be immobilized beforehand. It is not meant to be an enemy to fight, it is a caretaker for a clock tower that I want to be cursed/immobilized that the PC's can figure out and dispel/cure as part of a subplot device...

Clockwork creations, as their names suggests, must be wound up before they animate. The creator of a clockwork crafts a unique key for each creation. This key is typically inserted into the clockwork's back and turned clockwise to wind it. Turning the key counterclockwise has the effect of winding the machine down, though only a willing (or completely helpless) machine will allow itself to be unwound in this way, meaning either its creator or someone its creator has specifically designated can normally do so. Since each key is totally unique, construction of a new key (or bypassing a key entirely) requires a successful Disable Device check (DC = 20 + the clockwork's CR). Larger clockworks tend to have larger keys, and particularly huge keys require more than one set of hands to turn. Rather than seek assistance from other engineers, eccentric or hermetic inventors often rely upon other clockwork creations to help them turn keys or aid in the creation of more monumental constructs. Other times, engineers give copies of keys to their most trusted clockworks, which can be programmed to wind allies and even themselves as the situation requires.

Thank you for that. It is truly bizarre that it would not be mentioned in the clockwork golem write up.

Last paragraph in the source does hint at other methods (steam for example) powering the clockwork besides winding, so since this is a home game with rule of cool and story trumping RAW, I'm going to hand wave it for story purposes.